The BBC's Leo Kelion says Google's announcement sets up a Holiday face-off between the two companies. He writes:

"Apple's iPad may have dominated tablet sales to this point, but it now faces cheaper competitors with their own media ecosystems and - in the case of Samsung's new Nexus 10 - a higher-resolution screen.

"Purchase decisions may come down to brand loyalty: does a shopper identify with an Amazon, Apple, Google or Microsoft logo on the back of their device? This is still a very young market and the key players are essentially still in land grab mode."

As for prices, the Nexus 4 will start at $299 with no contract; the Nexus 7 at $199 and the Nexus 10 at $399. For comparison, the just-announced iPad mini starts at $329.